I use g8 Cat bolts for everything. Inexpensive and the quality is unsurpassed. Use a bolt that the grip length is as long as the width of the outside of the shakle or as close as you can get. if slightly long, use hardened SAE washers to make up the difference, but no more than 2. One under the head and one under the self locking nut. Don't use the nuts with the plastic insert, but rather the ones with the deformed thread. All are available from Cat